The following relates generally to wireless communications, and more specifically to power and bandwidth efficient true wireless stereo speakers.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. In a wireless communication system, such as a Bluetooth system, devices may communicate on at low power over short distances. In some examples, Bluetooth devices may utilize channels within the frequency band via spread-spectrum frequency hopping. In some examples, two or more devices communicating via Bluetooth protocols may communicate on an ad hoc network referred to as a piconet. Each piconet may include a master device and one or more slave devices. Timing information regarding the piconet may be determined based on the master device. In some examples, the master device may transmit in a first transmission time interval (TTI) (e.g., a first Bluetooth slot of a Bluetooth slot pair) and may receive transmissions from one or more slave devices of the piconet in a second TTI (e.g., a second Bluetooth slot of Bluetooth slot pair).
In some cases, Bluetooth devices may include, for example, a device such as a cell phone, smart phone, portable music player, or the like. Such a device may be in communication with one or more speakers (e.g., true wireless stereo (TWS) Bluetooth ear buds). A speaker, such as an ear bud (e.g., a primary ear bud), may be connected to the phone and may pass the information (e.g., timing information) of the piconet where the phone is the master device to the second ear bud (e.g., a secondary bud or sniffer bud). The secondary ear bud may sniff voice data between the primary ear bud and the phone. However, both the primary and the secondary ear buds may be subject to packet errors while receiving the data. Upon the closing of each enhanced synchronous connection oriented (eSCO) window, the primary earbud and the secondary earbud may cooperate with each other to retrieve any lost or unreceived data. This may be referred to as selective relay. Each eSCO window may include a transmission period and a retransmission period. In some cases, transmission or retransmission may be successfully completed, but ear buds may be configured to wait for the conclusion of the retransmission window of the eSCO window before implementing selective relay. Waiting to implement selective relay until after the close of an eSCO window may result in additional air time and excessive power expenditure.